In the past, containers (e.g., basins or tanks) have been provided to house apparatus in which materials are collected. For example, materials may be collected from liquids by plate or tube settlers that promote settling of the material to the bottom of the basin. In other cases, flocculators may be housed in such containers, and materials often inadvertently move in the flocculators to the bottom of the basin. Because the flocculators are designed to circulate the liquid and materials, rather than promoting settling of the materials, the materials that inadvertently collect at the bottom of the basin present a problem. In both cases, the materials on the bottom may be referred to as “sludge”.
In the case of the settlers, for example, the sludge is collected, or removed, from the bottom to make room for more materials as more liquid and materials flow into the basin. In the past, sludge collection equipment has been mounted on or near the bottom for gathering the sludge and flowing the sludge out of the basins. Such equipment has included a so-called header pipe (e.g., a hollow tube) mounted for movement along a path adjacent to the bottom. The header pipe is below the settler plates of a settler, for example. Low pressure has been applied to the header pipe as the header pipe moves along the path. Holes in the pipe admit the sludge and liquid from the bottom of the basin. The holes may be of the type described in U.S. Pat. No. 5,914,049, issued on Jun. 22, 1999, and entitled “Method and Apparatus For Helical Flow In Header Conduit”, the disclosure of which is incorporated by reference. Under the action of the low pressure, the sludge and the liquid flow into and through the header pipe, and from the header pipe through a flexible outlet hose to a discharge location out of the basin.
The low pressure has been applied to the header pipe by the flexible outlet hose. Such hoses have generally been small diameter hoses, e.g., not exceeding four inches in diameter. Also, the flexible hoses are typically ribbed on the inside, which restricts the inside diameter and increases head loss. Generally, such small diameter hoses can only induce a maximum flow rate of about 200 gallons per minute (gpm) in the header pipe. Thus, the flow rate through the header pipe has been limited by the flow capacity of the flexible outlet hoses.
An unacceptable solution to this flow rate problem is to use many of the flexible hoses. That solution is unacceptable because the flexible outlet hoses can flex. Each flexible hose is thus free to rise (i.e., float) above the header pipe under buoyancy forces of gases in the flexible outlet hose. As a result, the flexible hoses have in the past risen above the header pipe and a portion of each flexible hose has assumed an inverted U-shape. Unfortunately, because the U-shaped portion is above the level of the header pipe, and is above the level of an outlet of the flexible hose from the basin, the gas becomes trapped in such inverted U-shaped portion, making it difficult to prime the hose when starting the sludge collecting operation. When many flexible hoses are used to provide more flow rate from the header, the priming problem is increased.
Also, because the flexible outlet hoses tend to float, these hoses tend to interfere with the operation of the settlers, which extend downwardly in the basin toward the bottom and provide a low-clearance situation at the bottom of the basin. A similar problem would exist with attempts to use such hoses to remove the material from beneath the flocculators.
Embodiments described in the second parent application overcame all of the above limitations of the described prior systems, by providing a way of significantly increasing the flow rate through a header pipe that collects material from the bottom without causing the problems in priming the sludge collection system. Those embodiments also provided a way of achieving such sludge collection, while having an easily primed collection system, and provided the entire sludge collecting system in the low-clearance space under the settler and flocculating equipment that extends down near the bottom of the basin.
In the embodiments of the second parent application, the way of significantly increasing the flow rate through the one header pipe that collects material from the bottom was by using a larger-diameter pipe assembly connected to the header pipe. The way of avoiding problems in priming the sludge collection system was by making the larger-diameter pipe assembly rigid so that it was not free to rise (float) above the level of the header pipe in the basin, or the outlet of the pipe assembly, which is near the bottom of the basin. The way of achieving such sludge collection, while having an easily primed collection system, and providing the entire sludge collecting system in the low-clearance space under the settler and flocculating equipment that extends down near the bottom of the basin, was to mount the larger-diameter, rigid pipe assembly directly adjacent to the bottom of the basin, e.g., along the path normally taken by the header pipe as it traverses the bottom of the basin. That way of achieving these features, while still allowing the sludge collecting system to traverse the header from one end of the basin to the opposite end of the basin, was by making the larger-diameter rigid pipe assembly telescopic, that is, in two parts that have a telescopic relationship. In this manner, one telescopic pipe was secured to the basin, as by being held in place as it extends through an end wall of the basin to a sludge outlet outside the basin. Such fixed pipe was a pipe having a diameter larger than the small (e.g., maximum of four inches) prior flexible hoses described above. The other telescopic pipe was somewhat larger (e.g., about two inches larger) than the fixed pipe so as to receive the fixed pipe and permit relative movement between the two telescopic pipes. The fixed pipe was called the inner telescopic pipe and the other telescopic pipe was called the outer, or movable, telescopic pipe.
The movable outer pipe of the embodiments of the second parent application was configured to carry a plurality of the headers, and was moved by a low-profile cable drive relative to the bottom of the basin and between the end walls of the basin to present the headers to the sludge that accumulates on the bottom of the basin awaiting collection. The use of many such headers on the telescopic arrangement provided the advantage, for example, of allowing collection of the sludge simultaneously from many locations along the floor of the basin. However, Applicant's further studies of the flow characteristics of such plurality of headers indicated that it is desirable to provide additional benefits using the two telescopic pipes of the parent application. For example, during the use of more than one header on the two telescopic pipe arrangement, and without having moving parts in addition to the movement of the one pipe relative to the other pipe, there should be a way to assure a balanced flow of sludge and liquid through both header pipes. Also, again without having such moving parts, such studies indicated that it would be desirable to provide a way of obtaining a higher ratio of sludge to liquid collected by the telescopic arrangement. Further, such studies indicated that it would be desirable to provide a way to avoid sludge build-up near one end of the basin as compared to the sludge near the other end, by uniformly removing the sludge from across the area of the bottom of the basin.
What is needed then is a way to achieve the advantages of the telescopic pipe arrangement of the second parent application, and to have the additional advantages of allowing collection of the sludge simultaneously from many locations along the floor of the basin, and, without having moving parts in addition to the movement of the one pipe relative to the other pipe, to provide a way to assure a balanced flow of sludge and liquid through both header pipes. Also, again without having such moving parts, what is needed is to provide a way of obtaining a higher ratio of sludge to liquid collected by the telescopic arrangement. Further, what is needed is to provide a way to avoid sludge build-up near one end of the basin as compared to the sludge near the other end.